This invention relates to catalysts containing the element titanium formed by calcination in air of alumina hydrate which has been impreganted with a titanium compound.
The present invention has been found particularly useful in the preparation of hydro-desulfurization catalysts for the reduction in the sulfur compound content of petroleum oils and fractions thereof.
Such catalysts have been described in U.S. Pat. No. 3,840,473, to which reference may be had for certain of their characteristics.
The catalyst produced by the process disclosed in said patent is a substantially phosphate-free catalyst comprising a hydrogenating component selected from the group consisting of Group VI and Group VIII metals, for example, in the form of oxides and sulfides supported on a nonzeolitic carrier, which catalyst is provided with a minor amount of a Group IV-B metal.
The preferred carrier is as stated in said patent, alumina; other substantially phosphate-free nonzeolitic carriers such as are referred to in said patent may be used. The preferred metallic elements of Group VI metals is stated to be such as molybdenum and tungsten and metals of the iron group, such as cobalt and nickel and the metals of Group IV-B, i.e., titanium, zirconium, or hafnium. The proportions and ratio of the various metallic components are stated in the patent.
The procedure disclosed (see Example 1 of the patent) is a three-step process in which a calcined alumina is treated with an aqueous solution of ammonium paramolybdate in ammonium hydroxide. The treated alumina is dried and then impregnated with an aqueous solution of nickel nitrate. The treated product is then dried and calcined. The calcined product is impregnated with a solution of titanium tetrachloride in n-heptane. The treated product is dried and calcined. The resultant product contained nominally 8% molybdenum, 3% nickel, and 5% titanium, all by weight and based on the total catalyst. For details of the process as disclosed in Example 1, reference is made to the patent.
Commercial hydrodesulfurization catalyst of the Group VI and Group VIII type usually employs a carrier. The carrier as presently employed is a shaped particle herein referred to as a pellet.
Such particles for such purpose in commercial operations in the prior art have been formed of hydrated alumina, and shaped into cylindrical or spherical particles and dried and calcined for impregnation with the Group VI and Group VIII metal compounds.